Mitochondrial changes in flight muscles of normal and flightless Drosophila melanogaster with age.

Fine structural changes in mitochondrial morphology pertaining to size, number and growth were examined in flight muscles of normal and experimentally dewinged male Drosophila melanogaster ranging up to 26 days of age. In the normal winged flies, the number of mitochondria decreases during the first week of adult life whereas the size of individual mitochondrial profile increases significantly. Changes in mitochondrial size and number are due to the fusion of mitochondria. Fused mitochondria are are extremely large in size and irregular in shape. In 26-day old normal flies, the number of mitochondria increases while the mitochondrial size is recuced indicating mitochondrial division. In comparison to the normal flies, dewinged flies exhibit a similar degree of mitochondrial fusion and growth during the first week of life. However, the extent of mitochondrial fission in 26-day old dewinged flies is greater than in the normal flies of this age. Structural mechanisms of mitochondrial fusion and fission are described. The objective of this study was to examine the relative effects of age and flight activity on the mitochondria.